Loopo's questions

I have a server with a software RAID system.

There are 4 disk in the array:
4 x 4TB model WD40EFRX-68WT0N0

I noticed that the OS was reporting one of the disks to be 3TB, so I rebooted and checked in the BIOS and it also reports 3TB. Whereas it reports 4TB for the others.

The sticker on the physical disk says 4TB, just like the other 3. This disk has been in the server for several months with no problem. The only change I made recently is to update the OS (on a drive outside of the RAID).

I will replace the disk, but was wondering if anyone had seen this before and If there is a fix. Is it likely to be the HDD controller, the motherboard/bios (MSI/AMI), or something else? I put the drive in a different machine, and the BIOS there also reports 3TB.

Why is it exactly 3TB instead of 4? Seems too exact somehow.

more details on the drives: SATA, WD Red(tm), NASware(tm) 3.0

ADDTIONAL:

As per @shodanshok's request, here is the output from hdparm and smartctl. Looks like a Host Protected Area is enabled, and uses 1/4 of the drive.

$ sudo hdparm -N /dev/sda

/dev/sda:
max sectors   = 5860577134/7814037168, HPA is enabled

Can this have been set accidentally or by an OS install somehow?

and here's the output from smartctl:

$ sudo smartctl -a /dev/sda
 smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.19.0-32-generic] (local build)
 Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org

 === START OF INFORMATION SECTION ===
 Device Model:     WDC WD40EFRX-68WT0N0
 Serial Number:    WD-WCC4E5RZJJUE
 LU WWN Device Id: 5 0014ee 2b7895291
 Firmware Version: 82.00A82
 User Capacity:    3,000,615,492,608 bytes [3.00 TB]
 Sector Sizes:     512 bytes logical, 4096 bytes physical
 Rotation Rate:    5400 rpm
 Device is:        Not in smartctl database [for details use: -P showall]
 ATA Version is:   ACS-2 (minor revision not indicated)
 SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
 Local Time is:    Thu Apr 14 13:58:53 2016 IST
 SMART support is: Available - device has SMART capability.
 SMART support is: Enabled

 === START OF READ SMART DATA SECTION ===
 SMART overall-health self-assessment test result: PASSED

 General SMART Values:
 Offline data collection status:  (0x00)   Offline data collection activity
                                           was never started.
                                           Auto Offline Data Collection: Disabled.
 Self-test execution status:      (   0)   The previous self-test routine completed
                                           without error or no self-test has ever 
                                           been run.
 Total time to complete Offline 
 data collection:                  (53280) seconds.
 Offline data collection
 capabilities:                      (0x7b) SMART execute Offline immediate.
                                           Auto Offline data collection on/off support.
                                           Suspend Offline collection upon new
                                           command.
                                           Offline surface scan supported.
                                           Self-test supported.
                                           Conveyance Self-test supported.
                                           Selective Self-test supported.
 SMART capabilities:             (0x0003)  Saves SMART data before entering
                                           power-saving mode.
                                           Supports SMART auto save timer.
 Error logging capability:         (0x01)  Error logging supported.
                                           General Purpose Logging supported.
 Short self-test routine 
 recommended polling time:          (   2) minutes.
 Extended self-test routine
 recommended polling time:          ( 532) minutes.
 Conveyance self-test routine
 recommended polling time:          (   5) minutes.
 SCT capabilities:                (0x703d) SCT Status supported.
                                           SCT Error Recovery Control supported.
                                           SCT Feature Control supported.
                                           SCT Data Table supported.

 SMART Attributes Data Structure revision number: 16
 Vendor Specific SMART Attributes with Thresholds:
 ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
   1 Raw_Read_Error_Rate     0x002f   200   200   051    Pre-fail  Always       -       0
   3 Spin_Up_Time            0x0027   175   175   021    Pre-fail  Always       -       8241
   4 Start_Stop_Count        0x0032   100   100   000    Old_age   Always       -       14
   5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  Always       -       0
   7 Seek_Error_Rate         0x002e   200   200   000    Old_age   Always       -       0
   9 Power_On_Hours          0x0032   098   098   000    Old_age   Always       -       1992
  10 Spin_Retry_Count        0x0032   100   253   000    Old_age   Always       -       0
  11 Calibration_Retry_Count 0x0032   100   253   000    Old_age   Always       -       0
  12 Power_Cycle_Count       0x0032   100   100   000    Old_age   Always       -       14
 192 Power-Off_Retract_Count 0x0032   200   200   000    Old_age   Always       -       9
 193 Load_Cycle_Count        0x0032   200   200   000    Old_age   Always       -       1830
 194 Temperature_Celsius     0x0022   114   108   000    Old_age   Always       -       38
 196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   Always       -       0
 197 Current_Pending_Sector  0x0032   200   200   000    Old_age   Always       -       0
 198 Offline_Uncorrectable   0x0030   100   253   000    Old_age   Offline      -       0
 199 UDMA_CRC_Error_Count    0x0032   200   200   000    Old_age   Always       -       0
 200 Multi_Zone_Error_Rate   0x0008   100   253   000    Old_age   Offline      -       0

 SMART Error Log Version: 1
 No Errors Logged

 SMART Self-test log structure revision number 1
 No self-tests have been logged.  [To run self-tests, use: smartctl -t]


 SMART Selective self-test log data structure revision number 1
  SPAN  MIN_LBA  MAX_LBA  CURRENT_TEST_STATUS
     1        0        0  Not_testing
     2        0        0  Not_testing
     3        0        0  Not_testing
     4        0        0  Not_testing
     5        0        0  Not_testing
 Selective self-test flags (0x0):
   After scanning selected spans, do NOT read-scan remainder of disk.
 If Selective self-test is pending on power-up, resume after 0 minute delay.

I am running apache on an ubuntu installation. Several webapps are running on the same server.

I installed a new app, which required the pdo-sqlite extension to be installed.

Now my server is noticeably slower and doesn't seem to respond when asked for php generated CSS e.g. asking for:

  phpmyadmin/phpmyadmin.css.php  

gives an empty page (not a 404 error)

This seems to apply to all web-apps on the server where css is being generated from a php file. Other pages also show net::ERR_INCOMPLETE_CHUNKED_ENCODING in Chrome whereas Firefox doesn't complain.

Firefox says Status OK ... 0 bytes

Chrome is throwing up a load of net::ERR_INCOMPLETE_CHUNKED_ENCODING errors for all sorts of pages, not just the .css.php

The same webapps run perfectly fine on the development server. (no errors from Chrome and .css being returned from .css.php files)

things I tried:

• uninstalling php5-sqlite
• rebooting the server
• disabling pdo extensions in php
• checking for any .htaccess files

Any clues much appreciated.

The hostname of my server is slightly unfriendly (let's say b4dn4me). I want my users to be able to access the server under a nicer name (let's say bonnie).

Samba is installed just to be able to respond to windows netbios name queries (just need nmbd), not to run a windows fileshare.

In the smb.conf file you can add a line:

netbios aliases = bonnie <alias2>

I had the idea that since we can specify a netbios name, I could use that as an 'alias' instead

netbios name = bonnie

Neither of the above work, though I can connect to b4dn4me with no problem.

I tried enabling/disabling the lines wins support and wins server

I don't want anything fancy, like binding to different interfaces (eth0:1 eth0:2) or different configs depending on what name was used to access the server. All the material I found on the interwebs regarding this so far, have this type of complicated set-up.

All I want the server to respond to bonnie as well as b4dn4me.

I am in charge of maintaining around 25 PCs with various versions of Windows (Vista, 7, 8).

I was thinking something along the following lines:

• Every 4–6 months:
  • Take an image of the system partition so that installed programs with their various license requirements can be restored easily if a hard disk fails. (I am thinking of Clonezilla for this.)
  • Physically clean the machine, get rid of dust on the fans etc.
• Every 2 months:
  • Do a software check on things like backups still running ok, anti-virus up to date, Windows updating itself, firewall set up correctly.
• Every day:
  • Automatic backups of things like emails and documents.

What kind of schedule do you recommend?
What kind of software tools to use? Ideally I would like to automate as much of this as possible.
What other things should I be doing?

UPDATE:

Thanks for all the great answers so far, the advice to not do backups/images of individual machines doesn't really work in my case.
The licensing costs would be prohibitive, since there are at least 5 different software configurations for the different roles in the company -- finance, sales, management, production (3 types here alone) and having licenses for everyone for everything wouldn't make sense.
Also we have to keep some old versions of software for compatibility with some of our customers - the installation disks (with the license keys) have been lost or buried before my time.

I have a cronjob that calls a script. I want the output to be placed in a log file. The problem is that the log-file is created even if there is no output.

Since the job runs once an hour, and mostly has nothing to do. I am ending up with a lot of 0 byte files.

I could probably append to a single log file, but I wonder if there is a trick to use to prevent the log-file being created or to delete it if it is empty. (I don't really want to run a second cron-job to clean up after the first one)

A complication is the fact that the log filenames have a date/time appended to them. The line in crontab looks a bit like this:

/your/script.sh config.txt > outfilepath_`date +\%Y-\%m-\%d_\%H\%M`.html 

I guess that means I have to store the date in a variable first and then check if that file was created/empty. So if I take Stone's answer I end up with something like:

logfile=outfilepath_`date +\%Y-\%m-\%d_\%H`; your/script.sh config.txt > $logfile; if [! -s $logfile]; then rm $logfile; fi

but I don't know if that's possible inside crontab

I am trying to configure a new samba (3.6.9-151.el6) fileserver on CentOs 6.4

The browsing works, I can see the other Computers on the network using smbtree -N The server shows up in the list and is accessible under its dns/host name (FOO), which is different from its netbios name (BAR).

I want to be able to switch the netbios name if the fileserver fails, to something like BAR-BAD. And give the backup server the name BAR. This way I wouldn't need to reconfigure the windows clients' mapped drives.

[global]
log file = /var/log/samba/log.%m 
netbios name = BAR
local master = yes
workgroup = WORKGROUP 
os level = 99
encrypt passwords = yes
security = user
map to guest = Bad User
preferred master = yes
wins support = yes
guest ok = yes
wins proxy = no
dns proxy = no

When I do a nmblookup BAR from the server itself I get a failure on the netbios name BAR. It seems that the netbios name setting in smb.conf is being ignored. I have tried many combinations of settings of wins/ master browser / local browser ... to no avail.

Any clues as to what might be going on would be greatly appreciated.

My postfix (V: 2.5.5-1.1) running on ubuntu server (9.04) started to reject mail arriving in from outside about 2 weeks ago. Doing a "manual" session via telnet shows that the connection is always closed after the

MAIL FROM: [email protected] 

line is input, with the message "Connection closed by foreign host."

Doing the same from another client inside the LAN works fine. In the log files I get the line "lost connection after MAIL from xxxxx.tld[xxx.xxx.xxx.xxx]" This is after some lines like:

match_hostaddr: XXX.XXX.XXX.XXX ~? [::1]/128
match_hostname: XXXX.tld ~? 192.168.1.0/24
...
match_list_match: xxx.xxx.xxx.xxx: no match

which seem to suggest some kind of filter which checks for allowed addresses. I have been unable to locate where this filter lives, or how to turn it off. I'm not even sure if that's what's causing my problem. Connections from inside the LAN don't get disconnected even though they also show a "match_list_match: ... no match" line.

I didn't change any configuration files recently, below is my main.cf as it currently stands. I don't really know what all the parameters do and how they interact. I just set it up initially and it worked fine (up to recently).

smtpd_banner = $myhostname ESMTP $mail_name (GNU)
biff = no
readme_directory = no
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/server.crt
smtpd_tls_key_file=/etc/ssl/private/server.key
#smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtp_sasl_auth_enable = no
smtp_use_tls=no
smtp_sasl_password_maps = hash:/etc/postfix/smtp_auth
myhostname = XXXXXXX.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = XXXX.XXXX.com, XXXX.com, localhost.XXXXX.com, localhost
relayhost = XXX.XXX.XXX.XXX
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 192.168.1.0/24
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
smtpd_sasl_local_domain =
#smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_sasl_authenticated_header = yes
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_

when checking the process list, postfix/smtpd runs as

smtpd -n smtp -t inet -u -c -o stress  -v -v

Any clues?